A centrifugal multiblade fan includes a plate-shaped disc that has a protruding part at its center with a circular arrangement of a plurality of fan blades fixed at equal intervals to a periphery of the protruding part forming a sort of a pipe shape, each of the blades is thicker around the lifting line at the basal part near the disc and gradually gets thinner as one goes away from the basal part of the disc, to reduce noise and improve wind-blowing efficiency (see, for example, Patent Document 1).
Another conventional centrifugal multiblade fan includes a disc and a plurality of blades, in which each of the blades is circularly arranged about a common rotation axis in almost radial formation. When the fan rotates, a centrifugal airflow is created in a blower. Each of the blades is tapered in such a manner that a chord length towards the disc side, at least at an internal diameter tip becomes longer. The tapered tip has any one of a plurality of cuts, dents, and step-like bulges made at an angle that is suitable for cutting, to suppress separation of an airflow or generation of a turbulent eddy, and reduce noise (see, for example, Patent Document 2).                Patent Document 1: Japanese Patent Laid-Open No. S60-156997 (page 2, FIGS. 5 to 7.)        Patent Document 2: Japanese Patent Laid-Open No. 2001-234888 (Pages 3 and 4, FIGS. 1 to 3).        